Followers

Surveying

Surveying
is the process by which a surveyor measures certain dimensions that generally
occur on the surface of the Earth. Surveying equipment, such as levels and
theodolites, are used for accurate measurement of angular deviation, horizontal,
vertical and slope distances.Surveying
may be classified on the basis of nature of the survey field, object of survey,
instruments used and the methods
employed.

1. Classification Based on
Nature of Survey Field

This basis
survey may be classified as land survey, marine or hydraulic survey and
astronomical survey.

Land Survey: It involves measurement of various
objects on land. This type of survey may be further classified as given below:

(a)Topographic Survey: It is meant
for plotting natural features like rivers, lakes, forests and hills as
well as man made features like roads,
railways, towns, villages and canals.

(b) Cadastral Survey: It is for marking the boundaries of
municipalities, villages, talukas, districts, states etc. The survey made to
mark properties of individuals also come under this category.

(c) City Survey: The survey made in connection with the
construction of streets, water supply and sewage lines fall under this
category.

Marine or Hydrographic
Survey

Survey conducted to find depth of water at various points in bodies of
water like sea, river and lakes fall
under this category. Finding depth of water at specified points is known
as sounding.

Astronomical Survey

Observations made to heavenly bodies like sun, stars etc., to locate
absolute positions of points on the
earth and for the purpose of calculating local time is known as
astronomical survey.

2. Classification Based on
Object of Survey

On the basis
of object of survey the classification can be as engineering survey, military
survey, mines survey, geological survey and archeological survey.

(a) Engineering Survey: The objective of this type of survey is
to collect data for designing civil engineering projects like roads, railways,
irrigation, water supply and sewage disposals. These surveys are further sub-divided into: Reconnaissance
Survey for determining feasibility and estimation of the scheme. Preliminary Survey for collecting
more information to estimate the cost of the project, and Location Survey to set the work on the
ground.

(b) Military Survey: This survey is meant for working out
plans of strategic importance.

(c) Mines Survey: This is used for exploring mineral
wealth.

(d) Geological Survey: This survey is for finding different
strata in the earth’s crust.

(e) Archeological Survey: This survey is for unearthing relics of
antiquity.

3. Classification Based on Instruments Used

Based on the
instruments used, surveying may be classified as:

(i) Chain
survey

(ii) Compass
survey

(iii) Plane
table survey

(iv)
Theodolite survey

(v)
Tacheometric survey

(vi) Modern
survey using electronic distance meters and total station

(vii)
Photographic and Aerial survey

The survey is
taught to civil engineering students mainly based on this classification.

4. Classification Based on
Methods Employed

On this basis
surveying is classified as triangulation and traversing.

(i) Triangulation: In this method control points are
established through a network of triangles.

(ii) Traversing: In this scheme of establishing control
points consists of a series of connected points established through linear and
angular measurements. If the last line meets the starting point it is called as closed traverse. If it does not meet, it
is known as open traverse.